In die transfer systems of the subject character, a finger bar extends along one or both lateral sides of the die stations of a stamping press, and fingers extend inwardly from the finger bar or bars for engaging workpieces at the successive die stations. The finger bar or bars are driven longitudinally and laterally in synchronism with operation of the press for transferring workpieces through successive die stations and then out of the die. U.S. Pat. Nos. 4,032,018 and 5,307,666 each disclose die transfer systems of this general character, in which the finger bars are mechanically coupled by cam-and-follower arrangements to the ram of the stamping press for controlling operation of the finger bars. U.S. application Ser. No. 08/280,089, now U.S. Pat. No. 5,557,959, assigned to the assignee hereof, discloses an improved die transfer system in which the mechanisms for driving the finger bar(s) in lateral and longitudinal directions are provided as separate system modules.
In die transfer systems of the subject character heretofore proposed, replacement of the lateral finger bar drive mechanisms or modules to accommodate different workpieces or different dies, for example, normally requires either replacement or extensive rework of the longitudinal or transfer drive mechanism as well. That is, in typical conventional transfer system constructions, the transfer drive is specifically constructed for use in conjunction with a specific lateral drive construction, so that change-over of the die to manufacture a different part requires complete transfer system replacement. It is a general object of the present invention to provide a transfer module for a die transfer system that is readily adapted for use in conjunction with a variety of lateral drive modules, and may be readily configured for use in conjunction with differing lateral drive modules electronically and without requiring replacement of parts or components. Another and more specific object of the present invention is to provide a transfer module of the described character, and a drive transfer system embodying such transfer module, that may be readily programmed for use in conjunction with lateral drive modules of differing size, and longitudinal strokes of differing pitch.
A die transfer system for transferring workpieces between successive die stations in a stamping press includes an elongated finger bar having spaced fingers for engaging workpieces at successive die stations, a first drive module for reciprocating the finger bar laterally into and out of engagement with the workpieces at the die stations, and a second or transfer drive module for reciprocating the finger bar longitudinally for transferring workpieces between the successive die stations. In accordance with the presently preferred embodiment of the invention, the transfer drive module includes a transfer drive mechanism for placement adjacent to one longitudinal end of the finger bar, and a transfer coupling for releasably connecting the transfer drive mechanism to the finger bar for reciprocating the finger bar in the longitudinal direction between the successive drive stations. The transfer coupling is adjustably positionable laterally of the transfer drive mechanism for alignment with the finger bar, such that the transfer drive module is usable in conjunction with differing lateral drive mechanisms having different lateral positioning and motions of the finger bar.
In the preferred embodiment of the invention having finger bars that extend along opposed lateral sides of the die stations, a pair of laterally spaced transfer drive mechanisms are respectively positioned adjacent to the ends of the finger bars, and a bridge extends between the transfer drive mechanisms. A pair of carriages are mounted on the bridge and coupled by lead screws to respective stepper motors for adjusting position of each carriage laterally of the bridge independently of each other. Each carriage is coupled to an associated finger bar by a quick-disconnect coupling arrangement. In this way, the transfer drive mechanism may be readily disconnected from the lateral drive mechanisms for replacement of the latter, and may be readily readjusted for and connected to new lateral drive mechanisms of differing configuration.
The carriages in the preferred embodiment of the invention are coupled to respective associated sensors for providing a signal indicative of lateral position of each carriage. A controller receives signals indicative of desired position of each carriage, and controls motion of each carriage drive motor as a combined function of such desired position signal and position feedback signals from the carriage sensors. The quick-disconnect coupling for connecting the carriage(s) to the finger bar(s) in the preferred embodiment of the invention comprise a ball-and-socket connection arrangement that includes a ball mounted on each finger bar, an arm that extends from each carriage, and a socket at the end of each arm for releasably fastening the arm to an associated ball. A toggle clamp on each arm adjacent to the associated carriage is connected to a shaft that extends through the arm to a position adjacent to the socket for releasably capturing the ball. Each arm in the preferred embodiment of the invention is coupled to the associated carriage to pivot about a vertical axis as the finger bar moves laterally into and out of engagement with workpieces at the work stations, and about a horizontal axis as the finger bar moves vertically to raise workpieces from and place workpieces on the die stations.
The transfer drive mechanisms in the preferred embodiment of the transfer system comprise endless belt drive mechanisms. A single electric motor powers both transfer drive mechanisms by means of a shaft that extends laterally between the drive mechanisms. The shaft is a split shaft, having an inter-connection coupling for adjusting phase of the transfer drive mechanisms with respect to each other. Flags on one of the transfer drive mechanisms cooperate with proximity sensors for indicating limits of travel of the transfer drive mechanisms, and for indicating a home position of the transfer drive mechanisms. The electronic controller includes facility for programming offset from such home position to a start position for the transfer mechanisms as a function of the application in which the transfer system is employed.